Biological control of fungi associated with damping-off and root rot disease of cucumber ( Cucumis sativus L.)

Damping-off and root rot is a serious disease infecting cucumber on both seedling and adult stages. In this study, fifty-six fungal isolates were restored from cucumber plants showing typical symptoms of damping-off and root rot disease growing in different fields in Assiut governorate. These isolates were Pythium aphanidermatum (8 isolates), F. solani (12 isolates), Rhizoctonia solani (10 isolates), Drechslera halodes (12 isolates) and Macrophomina phaseolina (14 isolates). Pathogenicity tests revealed that these isolates were able to cause damping-off and root rot disease, however the most severe isolates were M. phaseolina isolate No 3 followed by R. solani No. 4, then F. solani isolate No. 6 as they caused root rot severity about 92.75, 91.5 and 76.75% respectively. In this study application of Gliocladium catenulatum, and Trichoderma harzianum proved to be an efficient antagonist to inhibit mycelial growth of plant pathogenic fungi in vitro, and to reduce the disease severity under greenhouse conditions, and significantly reduced the pre- and post-emergence damping off and root rot severity by rate of 50, 43.5, 52.33%, respectively in case of G. catenulatum and 60, 51.5, 53.32% in case of T. harzianum. These results proved that application of T. harzainum or G. catenulatum is an efficient method to control the causal pathogens of damping-off and root rot of cucumber.